Answer
$\begin{bmatrix} 3 & -4\\ 4& 48 \end{bmatrix}$
Work Step by Step
In order to multiply two matrices their dimensions must be same.
$D= \begin{bmatrix} -1 & 0\\ 2& 5 \end{bmatrix} \begin{bmatrix} -3 & 4\\ 2& 8 \end{bmatrix}\\=\begin{bmatrix} 3+(0)(2) & (-1)(4)+0 \\ -6+(5)(2)& 8+40 \end{bmatrix}\\=\begin{bmatrix} 3 & -4\\ 4& 48 \end{bmatrix}$
